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Abstract:

A method and system for a folding microfluidic device comprises creating
at least one folding line in a material, forming a plurality of layers of
a microfluidic device in said material, and folding the material at the
fold lines to create a self-aligned multilayered microfluidic device. The
material can comprise a carrier material with an adhesive layer on the
top and bottom surfaces.

Claims:

1. A method for fabricating microfluidic devices comprising: creating at
least one folding line in a sheet of material; forming a plurality of
microfluidic device components in said material; folding said material at
said fold lines; and adhering said folded material together to thereby
create a self-aligned microfluidic device.

4. The method of claim 3 wherein forming said plurality microfluidic
device components further comprises: forming at least one valve in at
least one of said layers of said material, such that said at least one
valve acts upon at least one fluid carried in at least one of said layers
of said material adjacent to said at least one valve; arranging a
plurality of microfluidic device components in said material; removing
parts of said material to form a plurality of microfluidic device
components; and arranging a flexible membrane between said at least two
layers of said material; and folding said at least two layers of said
material over said flexible membrane to thereby create at least one
microfluidic valve.

5. The method of claim 4 wherein said microfluidic valve comprises at
least one of: a pull-open valve; or a push-closed valve.

6. The method of claim 3 further comprising: removing sections of said
material to fit around and seal against at least one tubular enclosure;
arranging said fold lines to provide self alignment around said at least
one tubular enclosure; cutting at least one slot in a bottom of said last
folded layer to thereby create a fluidic connection between an inlet of
said microfluidic device and said at least one tubular enclosure to allow
a fluid to flow from said at least one tubular enclosure to said inlet of
said microfluidic device.

7. The method of claim 3 further comprising: arranging said fold lines to
form a three dimensional shape; folding said material along said fold
lines to form a three dimensional object comprised of said material
wherein both an inside surface of said three dimensional object and an
outside surface of said three dimensional object are accessible by a
fluid held in a wall of said three dimensional object.

8. The method of claim 7 wherein a plurality of properties of said fluid
in said walls of said three dimensional object can be manipulated at
different positions of said three dimensional object, said properties
comprising at least one of: fluid contents, flow rates, temperatures,
viscosities, opacities, and fluid mixings.

9. The method of claim 3 further comprising arranging a plurality of tabs
on said material to provide an alignment guide when said material is
folded at said fold lines.

10. A method for fabricating microfluidic devices comprising: creating at
least one folding line in a sheet of material; forming a plurality of
microfluidic device components in said material; arranging a plurality of
tabs on said material to provide an alignment guide; folding said
material at said fold lines and according to said alignment guide; and
adhering said folded material together; to thereby create a self-aligned
multilayered microfluidic device.

11. The method of claim 10 wherein forming said plurality microfluidic
device components further comprises: configuring said microfluidic device
as a plurality of layers of said material; forming at least one valve in
at least one of said layers of said material, such that said at least one
valve acts upon at least one fluid carried in at least one of said layers
of said material adjacent to said at least one valve; arranging a
plurality of microfluidic device components in said material; removing
parts of said material to form a plurality of microfluidic device
components; arranging a flexible membrane between said at least two
layers of said material; and folding said at least two layers of said
material over said flexible membrane to thereby create at least one
microfluidic valve wherein said microfluidic valve comprises at least one
of a pull-open valve or a push-closed valve.

12. The method of claim 10 further comprising: removing sections of said
material to fit around and seal against at least one tubular enclosure;
arranging said fold lines to provide self alignment around said at least
one tubular enclosure; cutting at least one slot in a bottom of said last
folded layer to thereby create a fluidic connection between an inlet of
said microfluidic device and said at least one tubular enclosure to allow
a fluid to flow from said at least one tubular enclosure to said inlet of
said microfluidic device.

13. The method of claim 10 further comprising: arranging said fold lines
to form a three dimensional shape; folding said material along said fold
lines to form a three dimensional object comprised of said material
wherein both an inside surface of said three dimensional object and an
outside surface of said three dimensional object are accessible by a
fluid held in a wall of said three dimensional object, wherein a
plurality of properties of said fluid in said walls of said three
dimensional object can be manipulated at different positions of said
three dimensional object, said properties comprising at least one of:
fluid contents, flow rates, temperatures, viscosities, opacities, and
fluid mixings.

14. A microfluidic device comprising: a material configured to have a
plurality of folding lines; a plurality of microfluidic device components
formed in said material; a plurality of tabs on said material to provide
an alignment guide when said material is folded at said fold lines; and
an adhesive, wherein said material is folded at said plurality of folding
lines and adhered together with said adhesive to thereby create a
self-aligned multilayered microfluidic device.

17. The device of claim 16 wherein said plurality microfluidic device
components further comprise: at least one valve in at least one of said
layers of said material, such that said at least one valve acts upon at
least one fluid carried in at least one of said layers of said material
adjacent to said at least one valve; wherein said material around said
plurality of microfluidic device components is removed; a flexible
membrane sealed between said at least two layers of said material thereby
creating at least one microfluidic valve.

18. The device of claim 17 wherein said microfluidic valve comprises at
least one of: a pull-open valve; or a push-closed valve.

19. The device of claim 16 further comprising: said material formed with
removed sections configured to fit around and seal against at least one
tubular enclosure wherein said fold lines provide self alignment around
said at least one tubular enclosure; and at least one slot formed in a
bottom of a last folded layer to thereby create a fluidic connection
between an inlet of said microfluidic device and said at least one
tubular enclosure, to allow a fluid to flow from said at least one
tubular enclosure to said inlet of said microfluidic device.

20. The device of claim 16 further comprising: a three dimensional shape
formed by the arrangement of said fold lines wherein said material is
folded along said fold lines to form walls of a three dimensional object;
and a fluid associated with said microfluidic device, wherein both an
inside surface of said three dimensional object and an outside surface of
said three dimensional object are accessible by said fluid held in said
walls of said three dimensional object.

Description:

CROSS-REFERENCE TO PROVISIONAL APPLICATION

[0001] This Application claims the benefit of priority based on U.S.
Provisional Patent Application 61/485,554 filed May 12, 2011 entitled
"FOLDABLE MICROFLUIDIC DEVICES USING DOUBLE-SIDED TAPE (INCLUDING
MICROVALVES, MANIFOLDS, AND DEVICES WRAPPED IN 3 DIMENSIONS)". The
above-referenced provisional patent application is hereby incorporated by
reference in its entirety.

TECHNICAL FIELD

[0002] Embodiments are generally related to the field of microfluidic
devices. More particularly, embodiments relate to methods and systems for
constructing microfluidic devices using adhesive materials such as
double-sided tapes and/or plastic laminates to create microvalves,
manifolds, and three-dimensional devices.

BACKGROUND OF THE INVENTION

[0003] The field of Microfluidics has created a demand for
micrometer-sized devices that can be used in a variety of applications
from medicine to ink jet printing.

[0004] However, fabrication of such devices can be time consuming,
complicated, and expensive. Therefore, a need exists for improved methods
and systems for fabricating microfluidic devices.

BRIEF SUMMARY

[0005] The following summary is provided to facilitate an understanding of
some of the innovative features unique to the embodiments disclosed and
is not intended to be a full description. A full appreciation of the
various aspects of the embodiments can be gained by taking the entire
specification, claims, drawings, and abstract as a whole.

[0006] It is, therefore, one aspect of the disclosed embodiments to
provide a method and system for fabricating microfluidic devices.

[0007] It is another aspect of the disclosed embodiments to provide for an
enhanced method and system for fabricating microfluidic devices with
microvalves and pneumatic elements.

[0008] It is another aspect of the disclosed embodiments to provide an
enhanced method and system for fabricating connector manifolds for
microfluidic devices.

[0009] It is another aspect of the disclosed embodiments to provide an
enhanced method and system for fabricating microfluidic devices which
incorporate fluid flow in three-dimensional objects.

[0010] It is yet another aspect of the disclosed embodiments to provide
for a method and system to deliver fluid to specific locations on a
three-dimensional object.

[0011] The aforementioned aspects and other objectives and advantages can
now be achieved as described herein. A method for fabricating
microfluidic devices comprises creating folding lines in a sheet of
material and forming a plurality of microfluidic device components in the
material. The material is then folded at the fold lines. This folded
material is then adhered together to thereby create a self-aligned
microfluidic device.

[0012] The microfluidic device can comprise a plurality of layers of the
material wherein the layers comprise at least one of polymers, plastics,
elastomers, paper, adhesive layers, liners, foil, porous materials,
glasses, and composites. The material is adhered using at least one of
adhesive tapes, chemical adhesive, mechanical pressure, electrostatic
attraction, melting, curable adhesive, epoxy, and urethane.

[0013] Forming the microfluidic device components further comprises
forming at least one valve in at least one of the layers, such that the
valve acts upon a fluid carried in one of the layers adjacent to the
valve. A plurality of microfluidic device components are arranged in the
material, and parts of the material are removed to form the microfluidic
device components. A flexible membrane is inserted and the material is
folded over the flexible membrane to create at least one microfluidic
valve. The microfluidic valve can be a pull-open valve or a push-closed
valve.

[0014] In an alternative embodiment of the invention sections of the
material are removed to fit around and seal against at least one tubular
enclosure. Next fold lines are arranged to provide self alignment around
the tubular enclosure. Cutting at least one slot in the bottom of the
last folded layer thereby creates a fluidic connection between an inlet
or outlet of the microfluidic device and the tubular enclosure to allow a
fluid to flow from the tubular enclosure to the inlet or outlet of the
microfluidic device.

[0015] An alternative embodiment of the invention comprises arranging the
fold lines to form a three dimensional shape by folding the material
along the fold lines to form a three dimensional object comprised of the
material wherein both the inside and outside surface of the three
dimensional object are accessible by a fluid held in the walls of the
three dimensional object. A plurality of properties of the fluid in the
walls of the three dimensional object can be manipulated at different
positions of the three dimensional object. These properties comprise at
least one of fluid contents, flow rates, temperatures, viscosities,
opacities, and fluid mixings.

[0016] In another embodiment of the invention a plurality of tabs are
arranged on the material to provide an alignment guide when the material
is folded at the fold lines.

[0017] In yet another embodiment of the invention a method for fabricating
microfluidic devices comprises creating at least one folding line in a
sheet of material, forming a plurality of microfluidic device components
in the material, arranging a plurality of tabs on the material to provide
an alignment guide, folding the material at the fold lines and according
to the alignment guide, and adhering the folded material together to
thereby create a self-aligned multilayered microfluidic device.

[0018] The method further comprises configuring the microfluidic device as
a plurality of layers of the material, forming at least one valve in at
least one of the layers, such that the valve acts upon at least one fluid
carried in at least one of the layers adjacent to the valve, arranging a
plurality of microfluidic device components in the material, removing
parts of the material to form a plurality of microfluidic device
components, arranging a flexible membrane, and folding the material over
the flexible membrane to create at least one microfluidic valve. The
microfluidic valve comprises at least one of a pull-open valve or a
push-closed valve.

[0019] In an alternative embodiment of the invention sections of the
material are removed to fit around and seal against at least one tubular
enclosure. Next fold lines are arranged to provide self alignment around
the tubular enclosure. Cutting at least one slot in the bottom of the
last folded layer thereby creates a fluidic connection between an inlet
of the microfluidic device and the tubular enclosure to allow a fluid to
flow from the tubular enclosure to the inlet of the microfluidic device.

[0020] Another alternative embodiment of the invention comprises arranging
the fold lines to form a three dimensional shape, folding the material
along the fold lines to form a three dimensional object comprised of the
material wherein both an inside surface of the three dimensional object
and an outside surface of the three dimensional object are accessible by
a fluid held in a wall of the three dimensional object. A plurality of
properties of the fluid in the walls of the three dimensional object can
be manipulated at different positions of the three dimensional object,
those properties comprising at least one of fluid contents, flow rates,
temperatures, viscosities, opacities, and fluid mixings.

[0021] In yet another embodiment a microfluidic device comprises a
material configured to have a plurality of folding lines. A plurality of
microfluidic device components are formed in the material. A plurality of
tabs on the material provide an alignment guide when the material is
folded at the fold lines. An adhesive binds the material after it is
folded at the plurality of folding lines and adhered together to create a
self-aligned multilayered microfluidic device.

[0023] In another embodiment the device further comprises at least one
valve in at least one of the layers, such that the valve acts upon at
least one fluid carried in the layers adjacent to the at least one valve.
The material around the plurality of microfluidic device components is
removed. A flexible membrane sealed between the at least two layers
thereby creates at least one microfluidic valve. The valve can be a
pull-open valve or a push-closed valve.

[0024] In another embodiment the device comprises the material formed with
removed sections configured to fit around and seal against at least one
tubular enclosure wherein the fold lines provide self alignment around
the tubular enclosure. At least one slot is formed in a bottom of the
last folded layer to thereby create a fluidic connection between an inlet
of the microfluidic device and the at least one tubular enclosure, to
allow a fluid to flow from the at least one tubular enclosure to the
inlet of the microfluidic device.

[0025] In another embodiment the device comprises a three dimensional
shape formed by the arrangement of the fold lines wherein the material is
folded along the fold lines to form walls of a three dimensional object.
A fluid is associated with the microfluidic device wherein in both an
inside surface of the three dimensional object and an outside surface of
the three dimensional object are accessible by the fluid held in the
walls of the three dimensional object.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying figures, in which like reference numerals refer to
identical or functionally-similar elements throughout the separate views
and which are incorporated in and form a part of the specification,
further illustrate the embodiments and, together with the detailed
description, serve to explain the embodiments disclosed herein.

[0031]FIG. 5a depicts a microfluidic device containing fluidic channels
and pull-open microvalves constructed from double-sided adhesive tape
before it has been folded;

[0032]FIG. 5b depicts an exploded top view of a pull-open microfluidic
valve associated with a microfluidic device constructed from double-sided
adhesive tape after it has been folded together to align the fluidic
channels and microvalving structures;

[0033]FIG. 5c depicts an exploded side view of a pull-open microfluidic
valve associated with a microfluidic device constructed from double-sided
adhesive tape after it has been folded together to align the fluidic
channels and microvalving structures;

[0034]FIG. 6a depicts a microfluidic device comprising a connector
manifold before it has been folded in accordance with an alternative
embodiment of the invention;

[0035]FIG. 6b depicts a microfluidic device comprising a connector
manifold being folded around a needle in accordance with an alternative
embodiment of the invention;

[0036]FIG. 6c depicts a microfluidic device comprising a plurality of
connector manifolds folded around needles in accordance with an
alternative embodiment of the invention;

[0037]FIG. 7 depicts the construction of a three-dimensional micro
fluidic device in accordance with another alternative embodiment of the
invention.

DETAILED DESCRIPTION

[0038] The particular values and configurations discussed in these
non-limiting examples can be varied and are cited merely to illustrate at
least one embodiment and are not intended to limit the scope thereof.
Various modifications to the preferred embodiments, disclosed herein,
will be readily apparent to those of ordinary skill in the art and the
disclosure set forth herein may be applicable to other embodiments and
applications without departing from the spirit and scope of the present
specification and the claims hereto appended. Thus, the present
specification is not intended to be limited to the embodiments described,
but is to be accorded the broadest scope consistent with the disclosure
set forth herein.

[0039]FIG. 1 illustrates a flow chart 100 of logical operational steps
for fabricating a microfluidic device in accordance with an embodiment of
the present invention. It should be appreciated that while FIG. 1
illustrates an exemplary series of steps for fabricating a microfluidic
device the order of these steps can be equivalently preformed in an
alternative order. The method begins at block 105.

[0040] Block 110 explains that layers for fluid and valving are created on
a material typically less than 500 micrometers in thickness such that
devices can be readily folded over a single fold line. This material can
be polymers, plastics, elastomers (e.g. poly(dimethylsiloxane)), paper,
adhesive, liners, foil, porous material, double-sided tape, glasses, and
composites. These materials can be used in any of the embodiments of the
invention described herein.

[0041] In the preferred embodiment illustrated in FIG. 1, double-sided
tape is used. Double-sided tape typically includes a carrier material
with an adhesive layer on the top and bottom and a removable liner
covering the adhesive layers. Preferred double-sided tapes for all the
embodiments described herein include double-sided silicone tape 3M 96042
or double-sided acrylic/silicone tape 3M 9731, but the choice of tape is
dependent on the materials being used.

[0042] Microchannels are created by cutting out parts of the double-sided
tape and covering it with a sheet of material--glass is preferable for
the base, plastics can alternatively be used as the top or bottom cover.
Microchannels can be created in plastics or other materials by embossing,
etching, or other ablation method. Any number of microfluidic device
components can be included on the tape. These might include, for example,
microchannels, microvalves or other pneumatic elements, diffusion
chambers, manifolds, holes that connect one layer to another (vias),
inlet and outlet ports, and other microfluidic device components.

[0043] In the present invention, the double-sided tape can be perforated
with doted or dashed cuts to create folding lines as described at block
115. This step also includes adding tabs along the edges of the tape.
These tabs are configured to match with tabs on the opposite side of the
folding lines to provide tactile alignment guides when the tape is
folded.

[0044] At block 120 the top liner protecting the adhesive on the tape is
removed and at block 125, a sheet of material, preferably an elastic
material such as poly(dimethylsiloxane) ("PDMS"), is attached to the top
adhesive surface of the tape as a membrane. PDMS is a silicone-based
organic polymer that is generally accepted as non-toxic, non-flammable,
and inert. In addition PDMS is viscoelastic making it an excellent choice
for the present invention. It should be noted that any similar material
could be used as the membrane described herein. In general, the membrane
will only be placed over the valving layer or the fluid layer so that
when the tape is folded at block 130, the membrane is sandwiched between
the two sides. Depending on where the fluids and valving lines are
connected to the device, vias may need to be created in the membrane to
allow fluids to move from one layer to another.

[0045] It will be appreciated that any number of adhesion methods may be
employed to bind the layers of material after folding at block 130. In
the embodiment described by FIG. 1 adhesive tape is used. In an
alternative embodiment the method of adhesion can be by chemical
adhesive, mechanical pressure, electrostatic attraction, melting, curable
adhesive, epoxy, urethane or other adhesive method.

[0046] After the membrane is attached, the tape can be folded along the
fold lines as illustrated at block 130. The tabs included in step 115,
can be used to ensure proper alignment of the folded sections of the
tape.

[0047] After the tape is folded, the liner covering the bottom layer
adhesive on the tape can be removed as shown at block 135. Block 140
describes that a one or more covers is then applied on or around the
layers of adhesive to enclose the channels that have been created in the
Microfluidic device. The cover(s) can be formed of plastic, PDMS or other
such material. The cover(s) can contain inlet holes where fluid and
valving inputs enter the microfluidic device. The method then ends at
block 145.

[0048] FIG. 2 depicts a high level flow chart 200 of logical operational
steps for fabricating microvalves or pneumatic elements in a microfluidic
device in accordance with an embodiment of the present invention. Note
that the steps illustrated in flow chart can be implemented in
conjunction with, or in addition to, those steps shown in flow chart 100.

[0049] In general, microvalves can be formed by creating a fluid layer and
a valving layer which are folded around a flexible membrane with vias
according to the method described above with respect to FIG. 1.
Microvalves can be formed as pull-open valves or push-closed valves.
FIGS. 5b and 5c illustrate a pull-open microvalve.

[0050] The method 200 begins at block 205. In a preferred embodiment of
the present invention a pull-open type microvalve can be created. At
block 210, the double-sided tape, or other such material disclosed above,
can have its liner cut away and removed above the valve seats. The rest
of the tape remains covered by the liner. At block 215 the valve seat can
be coated with nonstick coating such as Teflon spray, PDMS, or oil. These
steps render the valve seat operable and prevent the tape at the valve
seat from sticking to the membrane.

[0051] At block 240 the liner from this layer is removed and a membrane is
inserted. The tape is then folded at block 245 to enclose the membrane
between the fluid and valve channels. The other liner is then removed at
block 250 and a cover with inlet holes is placed around the device to
cover the tape as shown at block 255. This series of steps results in a
completed pull-open microvalve. The method ends at block 260.

[0052] In another embodiment of the invention, for creating pull-open type
microvalves, as shown at block 220, the tape liner is cut so that the
liner remains in place on top of the valve seat. Next, after the top
liner is removed, a membrane can be inserted at block 240 and sealed
between the layers at block 245. As shown at block 250, the bottom liner
can be removed and a cover can be applied to enclose the channels as
depicted at block 255. The method ends at block 260

[0053] Finally, in another alternative embodiment of the invention for
creating push-closed type microvalves, at 225 the bottom of the fluid
channels can be coated with uncured PDMS or other such material. Block
230 illustrates that the excess PDMS is removed. This step can be
accomplished using a spinning technique or using compressed air to blow
the remaining material away. The PDMS or other such material can then be
cured as shown at block 235 such that the bottom of the fluid channel is
rounded, which enables the membrane to completely seal against the bottom
of the fluid channel, thus completely closing the valve. In a related
alternative embodiment of the invention, the bottoms of the channels in
the fluid layer can be created to be naturally curved. This can be
achieved by embossing or other such known method.

[0054] After the material is cured, the top liner is removed and a
membrane can be inserted as shown at block 240. The membrane then is
sealed between the layers at block 245. Finally, the bottom liner is
removed at block 250 and a cover is applied at block 255 to enclose the
channels. This series of steps can be used to form a push-closed valve.
The method ends at block 250.

[0055] Incorporating microvalves and pneumatic elements is also
facilitated by using the folding lines described above to self align the
fluid and valve layers, which can be made of tape, or other such
material.

[0056] In another embodiment of the present invention connector manifolds
can be created by folding double-sided tape around a tubular structure,
such as for example a needle, which can, in turn stick to microfluidic
devices as shown by flow chart 300 in FIG. 3. This embodiment may be
implemented in accordance with, or in addition to the steps illustrated
in flow chart 100 and 200. This embodiment allows for rapid connections
of fluid reservoirs or pneumatic pressure lines with microfluidic
devices. This fabrication method can be completed very quickly, and can
be configured to allow multiple simultaneous connections. The method
begins at block 305.

[0057] Block 310 explains that the double-sided tape can be cut to allow
fitting around and sealing against a needle. In a preferred embodiment of
the invention a razor can be used to cut the double-sided tape. To
improve the sealing around the needle, the cutouts can be tapered so that
they are slightly larger than the needle diameter at the top
(approximately 25%) and slightly smaller than the needle diameter at the
bottom (approximately 25%).

[0058] In the embodiment of the invention in flow chart 300, folding lines
as in flow chart 100, are used to ensure the double-sided tape can be
easily folded to self align around the needle. In addition, as shown in
FIG. 6b, several layers may be needed to account for the relative
diameter of the needle.

[0059] Next at block 315, holes can be cut in the bottom of the last
folded layer to allow fluid to exit from the needles and connect to
inlets on a microfluidic device. In addition, as described at block 320,
the underside of the last fold of the double-sided tape can be used to
adhere to the microfluidic device. In a preferred embodiment this
adhesive can be acrylic, silicone, acrylic-silicone, or other such custom
adhesive.

[0060] At block 325 the bottom liner of the tape can be removed and at
block 330 the folded tape can be wrapped with a cover to enclose the
channels except where the tape is desired to stick to the microfluidic
device. The method ends at block 335.

[0061]FIG. 4 illustrates a high level flow chart 400 of logical
operational steps for constructing a three-dimensional fluid flow object.
Embodiments of the invention such as those shown in FIG. 4 have utility
in creating optical patterns, signal absorbance and transmittance, or
other dynamic patterns in or on an object that may contain a source or
detector. It may further provide opportunity as a physical standard or
phantom.

[0062] It should be noted that the method 400 disclosed herein shares
several steps with, for example methods 100, 200, and 300, and is
intended as an alternative embodiment of the present invention. The
method 400 and FIG. 7 describe an embodiment which contains an inner and
an outer fluidic layer separated by a middle layer (in this case not
intended for valving). The middle layer can be a flexible membrane if
valving elements are desired.

[0063] The method 400 begins at block 405. Block 410 explains that layers
for fluid and valving are created in a material with an adhesive layer on
the top and bottom (such as double-sided tape). It should be understood
that any material and/or adhesive described above with respect to FIGS.
1, 2, and 3 may equivalently be used with respect to the method 400. FIG.
7 illustrates such a product. Any number of microfluidic elements can be
included on the tape.

[0064] The double-sided tape can be perforated with dots or dashes in the
tape to create folding lines as described at block 415. The double-sided
tape should also be formed so that when it is folded along the folding
lines it will form into a three-dimensional object, such as a cube as
shown in FIG. 7 as element 705.

[0065] This step also includes adding tabs along the edges of the tape. In
this embodiment, in addition to facilitating folding alignment, the tabs
can contain channels and open holes (vias) that connect fluid from one
face of the device to another face when the faces are connected by
folding. The vias in the tabs align to holes in the faces of the device
in order to complete the fluidic connection of the faces.

[0066] At block 420 the top liner protecting the adhesive on the tape is
removed and at block 425, a sheet of material, preferably plastic or
PDMS, is attached to the top adhesive surface of the tape as a middle
layer. This layer may also contain microfluidic elements such as vias to
permit fluid to flow between the inner and outer layer of the device. At
block 430, the double-sided tape is folded over the middle layer along
the fold lines.

[0067] After the tape is folded, the liner covering the bottom (now outer)
layer of adhesive on the tape can be removed as shown at block 435. Block
440 describes that a second cover is then applied over the bottom layer
of adhesive to enclose the channels that have been created in the
Microfluidic device. The second cover can be formed of plastic, PDMS or
other such material and can contain vias to permit fluids and valving
lines to connect to the device. The adhesive face of the tabs will remain
uncovered such that the tape on the tabs can stick the faces together.

[0068] The device is then folded over the cover at block 445 and then
folded into a three-dimensional object along the folding lines at block
450. The method results in a three-dimensional object such as the
three-dimensional microfluidic cube shown in FIG. 7. The method then ends
at block 455.

[0069] The resulting three-dimensional structure allows fluidic access to
all the surfaces of the enclosed volume. This allows for dynamic fluid
flow in three dimensions. In addition, the invention creates a
three-dimensional volume that can be accessed through holes (vias) in the
microfluidic layers. The three-dimensional object may enclose a volume
(such as the cube shown in FIG. 7), or remain open. Both the inside and
outside of the three-dimensional object are accessible by the fluids
within the walls of the object. The layers can also contain pneumatic
objects.

[0070]FIG. 5a illustrates a microfluidic device 500 in accordance with
the present invention. In one embodiment dotted or dashed cuts 505 can be
made in a double-sided tape, or other such material, 510 to create
folding lines 515. In essence, folding lines separate different layers.
Double-sided tape 510 is generally covered by a liner that must be
removed before the adhesive is available. Channels 525 can be cut in the
tape. It may be desirable to define multiple layers in the tape such as a
valving layer 536, and a fluid layer 535.

[0071] Folding lines 515 can be used to facilitate self-alignment of the
tape 510 when it is brought together to form a micro-fluidic device 500.
A sheet of plastic or PDMS 520 can be sandwiched between the folded
double-sided tape 510 to create the top and bottom of channels 525 and to
serve as a pneumatic element to open and close fluid channels. The fluid
channels allow fluid flow through the fluid layers 535 unless pressure
actuates an aligned valve element in the valving layer 536 to stop fluid
flow. Other microfluidic device components can include vias, manifolds
and other fluid or pneumatic elements.

[0072] Unique tabs, such as tab 530 can be shaped into the edges of
double-sided tape 510 to aid in the tactile alignment of the layers. It
should be appreciated that while microfluidic device 500 is a simple
device with a single fold, much more complicated devices with multiple
folds and layers could be created. Tabs such as tab 530 can be important
in aligning such complicated devices.

[0073] Once the Microfluidic device 500 has been folded along the folding
lines 515 and around the PMDS 520, the covering over the other side of
the adhesive tape can be removed and a cover (not shown) can be wrapped
around the device to enclose the layers.

[0074] FIGS. 5b and 5c illustrate a detailed view of a valve that may be
included in microfluidic device 500. FIG. 5b illustrates a top view of a
pull-open microfluidic valve 540, created in double-sided tape 510. Note
that in FIGS. 5b and 5c, fluid layer 535 and valving layer 536 have been
folded together to create the microfluidic device. The top view of the
microfluidic valve illustrates a detailed view of the valve including the
valve seat 545, fluid channel 555, and valve channel 550.

[0075]FIG. 5c illustrates two side views of a pull-open microfluidic
valve 540. The valve seat 545 is held closed in the upper view 560. In
upper view 560, the valve does not allow fluid flow as illustrated by
arrow and label "closed" 570. In lower view 565, suction 580 holds the
valve seat 545 open so that fluid can flow as illustrated by arrow and
label "open" 575.

[0076]FIG. 6a illustrates a microfluidic device 500 comprising a
connector manifold to seal around tubular structures such as needles and
to provide a fluidic connection to remaining elements of the device. The
double-sided tape 510 can be patterned with folding lines 515. In
addition, the tape is cut with fittings 605. Fittings 605 can be cut to
be slightly larger than the needle 610 diameter at the top to slightly
smaller than the needle 610 diameter at the bottom. In a preferred
embodiment, the fitting size is 25% greater than the needle diameter at
the top and 25% less than the needle diameter at the bottom.

[0077] Double-sided tape 510 also includes a hole 615 in the bottom of the
last folded layer to allow fluid to exit the needles and connect with the
microfluidic device. The present embodiment allows for a rapid connection
of a fluid source and can withstand a relatively high pressure. Thirty
pounds per square inch of fluid pressure on a 21 gauge needle is readily
achievable.

[0078]FIG. 6b illustrates the present embodiment of a microfluidic
device. It may be necessary to include multiple layers 620 so that the
double-sided tape 515 is folded to be thick enough to enclose the needle
610 as shown in FIG. 6b.

[0079]FIG. 6c illustrates a completed microfluidic device 500 in
accordance with the present embodiment. It should be noted that, as shown
in FIG. 6c a number of needles 610 can be connected to the microfluidic
device via inlet 625. In addition, the embodiment is both reusable and
removable if necessary. These manifolds can also be fabricated as part of
a single microfluidic system.

[0080]FIG. 7 illustrates steps 700 for forming a three-dimensional
microfluidic device 705 which contains two fluidic layers (an inner and
an outer layer) that can be connected through vias in the middle layer
520. The microfluidic device 705 provides fluidic access to all of the
surface around and enclosing a volume. As with the other embodiments of
the present invention, the double-sided tape or other such material 510
must be shaped correctly so that the folds along fold lines 515 result in
the desired three-dimensional object 705. This may include forming the
double-sided tape 510 to be foldable into a three-dimensional shape and
cutting folding lines 515.

[0081] At step 1 the liner on one face of the double-sided tape is
removed. Then at step 2 a middle layer formed of plastic or PDMS sheet
520 is attached to half of the 3D object. Next at step 3, the
double-sided tape 510 is folded on itself and around the middle layer 520
as shown. The underside (now outside) of the double-sided tape has a
liner, which is also removed at step 4, and a plastic or PDMS sheet 710
is attached as a cover at step 5. The device, which includes tape 510, is
then further folded at step 6 to enclose the channels. The cover 710 can
also contain vias which facilitate fluidic and pneumatic elements
entering the device from the outside or accessing the inner volume of the
device.

[0082] The double-sided tape 510 is now ready to be folded into a
three-dimensional microfluidic device 705, as shown at step 7. The final
product is a three-dimensional microfluidic device 705. While the
microfluidic device 705 is illustrated as a cube it should be appreciated
that any number of other shapes can easily be formed according to the
illustrated steps.

[0083] Based on the foregoing, it can be appreciated that a number of
embodiments, preferred and alternative, are disclosed herein. For
example, in one embodiment, a method for fabricating microfluidic devices
comprises creating folding lines in a sheet of material and forming a
plurality of microfluidic device components in the material. The material
is then folded at the fold lines. This folded material is then adhered
together to thereby create a self-aligned microfluidic device.

[0084] The microfluidic device can comprise a plurality of layers of the
material wherein the layers comprise at least one of polymers, plastics,
elastomers, paper, adhesive layers, liners, foil, porous materials,
glasses, and composites. The material is adhered using at least one of
adhesive tapes, chemical adhesive, mechanical pressure, electrostatic
attraction, melting, curable adhesive, epoxy, and urethane.

[0085] Forming the microfluidic device components further comprises
forming at least one valve in at least one of the layers, such that the
valve acts upon a fluid carried in one of the layers adjacent to the
valve. A plurality of microfluidic device components are arranged in the
material, and parts of the material are removed to form the microfluidic
device components. A flexible membrane is inserted and the material is
folded over the flexible membrane to create at least one microfluidic
valve. The microfluidic valve can be a pull-open valve or a push-closed
valve.

[0086] In an alternative embodiment of the invention sections of the
material are removed to fit around and seal against at least one tubular
enclosure. Next fold lines are arranged to provide self alignment around
the tubular enclosure. Cutting at least one slot in the bottom of the
last folded layer thereby creates a fluidic connection between an inlet
or outlet of the microfluidic device and the tubular enclosure to allow a
fluid to flow from the tubular enclosure to the inlet or outlet of the
microfluidic device.

[0087] An alternative embodiment of the invention comprises arranging the
fold lines to form a three dimensional shape by folding the material
along the fold lines to form a three dimensional object comprised of the
material wherein both the inside and outside surface of the three
dimensional object are accessible by a fluid held in the walls of the
three dimensional object. A plurality of properties of the fluid in the
walls of the three dimensional object can be manipulated at different
positions of the three dimensional object. These properties comprise at
least one of fluid contents, flow rates, temperatures, viscosities,
opacities, and fluid mixings.

[0088] In another embodiment of the invention a plurality of tabs are
arranged on the material to provide an alignment guide when the material
is folded at the fold lines.

[0089] In yet another embodiment of the invention a method for fabricating
microfluidic devices comprises creating at least one folding line in a
sheet of material, forming a plurality of microfluidic device components
in the material, arranging a plurality of tabs on the material to provide
an alignment guide, folding the material at the fold lines and according
to the alignment guide, and adhering the folded material together to
thereby create a self-aligned multilayered microfluidic device.

[0090] The method further comprises configuring the microfluidic device as
a plurality of layers of the material, forming at least one valve in at
least one of the layers, such that the valve acts upon at least one fluid
carried in at least one of the layers adjacent to the valve, arranging a
plurality of microfluidic device components in the material, removing
parts of the material to form a plurality of microfluidic device
components, arranging a flexible membrane, and folding the material over
the flexible membrane to create at least one microfluidic valve. The
microfluidic valve comprises at least one of a pull-open valve or a
push-closed valve.

[0091] In an alternative embodiment of the invention sections of the
material are removed to fit around and seal against at least one tubular
enclosure. Next fold lines are arranged to provide self alignment around
the tubular enclosure. Cutting at least one slot in the bottom of the
last folded layer thereby creates a fluidic connection between an inlet
of the microfluidic device and the tubular enclosure to allow a fluid to
flow from the tubular enclosure to the inlet of the microfluidic device.

[0092] Another alternative embodiment of the invention comprises arranging
the fold lines to form a three dimensional shape, folding the material
along the fold lines to form a three dimensional object comprised of the
material wherein both an inside surface of the three dimensional object
and an outside surface of the three dimensional object are accessible by
a fluid held in a wall of the three dimensional object. A plurality of
properties of the fluid in the walls of the three dimensional object can
be manipulated at different positions of the three dimensional object,
those properties comprising at least one of fluid contents, flow rates,
temperatures, viscosities, opacities, and fluid mixings.

[0093] In yet another embodiment a microfluidic device comprises a
material configured to have a plurality of folding lines. A plurality of
microfluidic device components are formed in the material. A plurality of
tabs on the material provide an alignment guide when the material is
folded at the fold lines. An adhesive binds the material after it is
folded at the plurality of folding lines and adhered together to create a
self-aligned multilayered microfluidic device.

[0095] In another embodiment the device further comprises at least one
valve in at least one of the layers, such that the valve acts upon at
least one fluid carried in the layers adjacent to the at least one valve.
The material around the plurality of microfluidic device components is
removed. A flexible membrane sealed between the at least two layers
thereby creates at least one microfluidic valve. The valve can be a
pull-open valve or a push-closed valve.

[0096] In another embodiment the device comprises the material formed with
removed sections configured to fit around and seal against at least one
tubular enclosure wherein the fold lines provide self alignment around
the tubular enclosure. At least one slot is formed in a bottom of the
last folded layer to thereby create a fluidic connection between an inlet
of the microfluidic device and the at least one tubular enclosure, to
allow a fluid to flow from the at least one tubular enclosure to the
inlet of the microfluidic device.

[0097] In another embodiment the device comprises a three dimensional
shape formed by the arrangement of the fold lines wherein the material is
folded along the fold lines to form walls of a three dimensional object.
A fluid is associated with the microfluidic device wherein in both an
inside surface of the three dimensional object and an outside surface of
the three dimensional object are accessible by the fluid held in the
walls of the three dimensional object.

[0098] It will be appreciated that variations of the above-disclosed and
other features and functions, or alternatives thereof, may be desirably
combined into many other different systems or applications. Also, that
various presently unforeseen or unanticipated alternatives,
modifications, variations or improvements therein may be subsequently
made by those skilled in the art which are also intended to be
encompassed by the following claims.